Water rotor machines (or water wheels) are quite old in the art, and have been in use for centuries. Many water rotors are known as "turbines" and typically have a large vertical drop through which the water travels before striking the blades of the turbine, thereby gaining velocity to apply a greater force. Other water rotors or water wheels are submerged and use an inlet and an outlet through which the passage of the water is directed.
An example of a conventional water wheel having an inlet and outlet is U.S. Pat. No. 5,440,175 (by Mayo), which discloses a water wheel-driven generating unit that is to be used at a low head dam site. The inlet to the water wheel is an adjustable chute that extends from the dam crest to the water wheel. The Mayo water wheel has rotating longitudinal buckets (i.e., blades) that are designed to develop maximum energy over a wide range of flow conditions, and also to discharge debris. The buckets are vented as necessary to improve filling and discharge, and also to minimize vibration. Retention of water in the buckets until each one reaches the lowest point of travel is provided by an adjustable shroud. The shape of the bucket periphery is curved from an angle parallel to the chute at its lowest slope to an angle passing through the center of rotation of the water wheel, with the outer curved radius equal to one-half the bucket depth. The shroud can be moved away from the main housing to allow debris to be dislodged. Vents are provided near each bucket to allow an escape path for any air trapped between the filling water as the buckets rotate. Later, as the buckets become empty of water, air must take its place and the vents are designed to allow air back into the bucket to create smooth water dumping.
U.S. Pat. No. 1,293,110 (by Karafas) discloses a water wheel used on a ship, having an inlet and an outlet at the bottom. The blades of the impeller have a generally curved appearance and are very closely spaced together, essentially comprising pairs of half-blades that are mounted into one overall junction near the hub of the wheel.
U.S. Pat. No. 4,436,480 (by Vary) discloses a hydro-turbine apparatus to generate electricity. The turbine spins in the vertical plane and is designed to be submerged in a channel of water that will spin its vanes upon impact. On the inlet side of the turbine, a scoop member captures water flowing toward the turbine wheel and directs it behind each of the rotating vanes. This arrangement dumps water behind the rotating vanes at the earliest advantageous moment, since normally water would not effectively act on a vane until it is about to its horizontal position. The inlet and outlet of the turbine wheel are approximately 180 degrees from one another along the rotational movement of the vanes.
Some of the prior water wheels are provided with a buoyant rotatable drum in which the blades travel both through liquid and through a gas (i.e., air). For example, U.S. Pat. No. 2,097,286 (by McGee) discloses a power generating apparatus that uses a water wheel that is placed in a river. The McGee water wheel has curved blades that run parallel to one another, and have a somewhat concave shape to catch the current flow of the water. The water wheel is buoyant, and can rise or fall with the water level of the river. A vertical post is embedded in the river bottom, and an arm is pivotally attached by a pivot pin to the post. A DC generator is mounted within the interior of the cylindrical drum that holds the water wheel and its parallel blades.
Another patent that discloses a water wheel in which blades can protrude into air is U.S. Pat. No. 4,519,742 (by Van Buytene) which discloses a water wheel-type device that has a rotatable shaft with blades that are moved by flowing water. Each of the blades has at least one gate and a slide that can move the gate from an open to a closed position. When the gate is in its open position, it will allow fluid to pass through a corresponding opening in the blade. This would occur when the blade is protruding into air, so as to minimize friction caused by the air against the blade. When the blade enters the water, the gate slides to its closed position so that the water will impact against the gate to help force the blade to rotate in the proper direction.
U.S. Pat. No. 646,713 (by Symons) discloses a water wheel comprising a drum having hinged blades that present their surfaces in desirable positions while in the water, and do not waste the power of the wheel by forcing the water downward as they enter the water, or by lifting water as they rise or by encountering an unnecessary resistance of air as they rotate out of the water. The blades at positions "i.sup.15 " and "i.sup.16 " catch the water flow as the blades are about to leave the liquid domain and enter the gaseous domain. Once the blades are out of the water, the blades, by their own weight, pivot to the positions shown as "i.sup.1 " and "i.sup.2 ", and come to rest against an arm "n". The blades stay in that relative position until the blades are about to re-enter the water, at which time the blades further pivot to a position that is radial with respect to the center of the water wheel. This is illustrated by the dashed lines in the lower left quadrant and the very middle bottom spoke of the water wheel on FIG. 2. According to Symons, the blades are in their "feathered" position, ostensibly to minimize their friction or drag upon re-entering the water. After the blades have passed again into the water, they stay in the feathered position until they have rotated another 90 degrees, and they finally begin to pivot again so that they will catch the water and can then further help to propel the water wheel when back at their original positions at i.sup.15 and i.sup.16. There is some inefficiency in this design, particularly since the blades must re-pivot while they are already in the water, and thereby provide no thrust during the re-pivoting that would help propel the rotation of the water wheel.
It would be advantageous to provide a water rotor having a greater efficiency by capturing the water for a very large portion of the rotational travel of the blade of the water rotor. For water rotors that are buoyant and have blades that travel through the air for a portion of their rotation, it would be advantageous to minimize the air friction or wind resistance of the rotating blades during the portion of rotation that they travel through the air, especially at times when the air is moving in a direction that generally opposes such rotation.